In many cancers, aberrant DNA methylation of so called "CpG islands", CpG-rich sequences frequently associated with promoters or first exons, is associated with the inappropriate transcriptional silencing of critical genes. There is also a growing awareness that overall patterns of genomic DNA methylation play a critical role in the molecular characteristics of neoplastic disease. These DNA methylation events represent an important tumor-specific marker occurring early in tumor progression and one that can be easily detected by PCR based methods in a manner that is minimally invasive to the patient. In the case of head and neck squamous cell carcinoma (HNSCC), a disease of multifactorial etiology and great variability in risk factors, there is also considerable variability in promoter methylation events among the tumor population. This makes a high- throughput approach an intriguing means to identify prognostic epigenetic markers in HNSCC disease. The goal of this research project is therefore to classify the patterns of DNA methylation events in oropharyngeal squamous cell carcinoma (OPSCC), one subtype of HNSCC, and to identify specific DNA methylation "signatures" that can be used to predict tumor behavior and patient outcome. The specific aims of the project are: 1) To test the hypothesis that the pattern of global DNA methylation in a OPSCC clinical specimen contains information that can be used as a prognostic biomarker and a molecular classifier of this disease. 2) To test the hypothesis that there exists a CpG island methylator phenotype (CIMP) for OPSCC, and that this phenotype has prognostic value for this disease. 3) To test whether the aberrant methylation events identified in Aim 1 are observed in histologically normal tissues adjacent to the tumor, as well as in contralateral normal tissue. PUBLIC HEALTH RELEVANCE: Despite interventions, recurrence of the head and neck squamous cell carcinoma is observed in about 50% of patients, either locally, regionally or at a distant site with high rates of associated mortality. To date, few molecular markers have been found that can be reliably used in early detection of HNSCC or as indicators of prognosis. There is therefore an increasing necessity for better molecular classification of head and neck tumors to provide prognostic as well as predictive information to improve patient care.